xenomai: integration and qualification of a real time...

Xenomai

G.GOAVEC-MEROU

Xenomai

Hardware

Integration

Qualification

Evaluationtools

Conclusion

Xenomai:integration and qualification

of a real time operating systemARMadeus Systems

Gwenhael GOAVEC-MEROU

8 july 2009

G. GOAVEC-MEROU Xenomai 1 / 22

Xenomai

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Hardware

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Qualification

Evaluationtools

Conclusion

Plan

1 Xenomai

2 Hardware

3 Integration of Xenomai in a Buildroot environment

4 Qualification

5 Evaluation tools

6 Conclusion


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Xenomai: basics

Real time extension for Linux.Second kernel in charge of real time tasks→ Linux stays in charge of shared time applicationsKeep existing working environment and applicationsEasy port of applications to a real time environment


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Xenomai: structure

AdeosXenomai

concurrent accessto hardwaresoftwarecooperative withLinuxeasy port ofapplications

rt_task

Hardware

Adeos/I−pipe

Domain B Domain A

skin

s rt_task

rt_taskprocess

user

spa

ceke

rnel

spa

ce

Linux Xenomai Nucleus


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Hardware platform

APF9328 board:based on a Freescale i.MX CPUproviding an ARM9 core16 MB RAMXilinx Spartan 3 FPGA shares data,adress and control busses with theCPU

OE_nEB3_nChip_SelectHorloge

Interruption


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Integration of Xenomai

No packages for Xenomai in Buildroot frameworkmanual install

Patch:

Ipipe provided by AdeosXenomai applied to Linux by prepare kernel

Configure and compile kernelCompile and install libraries in user space

Complex and time consumingAutomated install

Interaction with the kernelLibraries

Xenomai installs immediately


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Presentation

Objective:monitor the performances of applications.Concept:generate signals using dedicated hardware (synthesizer) anddisplay the results on a digital storagescope.An application loads the system to disturb the periodicphenomenom

Carte APF 9328

Oscilloscope

Synthétiseurbasse fréquence

Lcd

voie1 voie2

PA.6 PA.9GPIO


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Qualification: principle

Two kinds of behaviours are observed:Periodic timer handlingHardware interrupt servicing

Exemples are tested in user space and kernel space, Linux andXenomai.


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Periodic timer handling: user space

Linuxdeclare a handler:sa.sa handler = isr ;sigaction (SIGVTARLM, &sa, NULL);trigger the counter:setitimer (ITIMER VIRTUAL, &timer, NULL);

Xenomaiconfigure the counter:rt task set periodic (NULL, TM NOW,SLEEP);

wait:rt task wait period (NULL);

40 ms

incertitudes


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Results: periodic timer in user space

(a) Linux, 5ms/div (b) Xenomai, 20µs/div

Linux Xenomaimin ? -32max ? +74,9


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Qualification: summary

Xenomai available on an ARM9 architectureBetter global performances on a weakly loaded OSBetter tolerance to loadingExpensive tools, hardly convenient and not always suitable:

2 GS/s digital storagescope ⇒ 40.000 euros.Connect GPIO outputsResults are not always usable (counter on Linux).


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Evaluations tools: concept

Purpose:no additional hardwareno changes to the kernel

LCD

Principle:use the FPGAable to measure performances of several codes at a given timeusable in user space and kernel space under Linux andXenomai.


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Structure

VHDL components:acquire and store mesurementsgenerate signals

kernel module:configure IPs.transfer (read) acquired data

MACROS:atomicusable in user space and kernel spacecan be disabled


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FPGA part

Multiple measurementsCompatible with data transfer on a Wishbone busUses POD

IP_xxx

logger

i2cocore00irq


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VHDL components


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Measurements

Replaces the oscilloscope.Computes and stores the time differences between start and stopevents

STARTSTOPRESET

Store the current counter value


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Measurements


STARTSTOPRESET

recover the starting valuecomparison with the current valueincrease cycle numberupdate minupdate max


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Measurements


STARTSTOPRESET

minmaxnumber of cyclesduration of the test


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Event gen

Configurable signal generatorRemplaces the dedicated hardware synthesizerInteraction with Measure and the application


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Kernel module

Access:/proc/driver/dev

LOGGER GET ID

LOGGER MEMBASE

/proc/drivers/log0

attrnametype pid

measuresminmaxnb_trignb_meastotal_time

paramstriggerext_startext_stopreset

clockstartstopadd

delprescaler


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MACROS

Known and deterministic access time ⇒ memory mapped datatransfers

CREATE ALL(nom)OPEN LOGGERFPGA START(nom)FPGA STOP(nom)

. . .i n t main ( void ) {

OPEN LOGGER( ) ;CREATE ALL( foo ) ;. . .

FPGA START( foo ) ;// Code a t e s t e rFPGA STOP( foo ) ;. . .

}


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Evaluation tools: summry

AutonomousSimple to useQuantitative data

oscilloscope toolmin max min max

Linux ? ? -1540 42439Xenomai -32 +74,9 -25 100


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Conclusion

Xenomai Buildroot Package availableXenomai runs on APF9328.Embedded evaluation tools for quantitative analysis ofapplications and kernel modules


Xenomai

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Questions

questions ?http://www.armadeus.org

http://sourceforge.net/projects/periphondemand


http://www.armadeus.org

http://sourceforge.net/projects/periphondemand

xenomai: integration and qualification of a real time...

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